To assess hormonal responses to Lupron in 14-18 year old, normal, gonadotropin deficient (GnD) and constitutional delayed (CD) teenagers so as to test the hypotheses that 1) the hormonal response to a single Lupron dose of 10mcg/kg SC will distinguish GnD from CDP, 2) the hormonal response to 2 doses at 5-day intervals will distinguish between GnD and CDP better than those to first Lupron dose.